World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0007337291
Reproduction Date:

Title: Dlco  
Author: World Heritage Encyclopedia
Language: English
Subject: Respiratory physiology, Spirometry, Caplan's syndrome, Bronchiolitis obliterans organizing pneumonia, Interstitial lung disease
Collection: Respiratory Physiology
Publisher: World Heritage Encyclopedia


DLCO or TLCO (diffusing capacity or transfer factor of the lung for carbon monoxide (CO),[1]) is the extent to which oxygen passes from the air sacs of the lungs into the blood. Commonly, it refers to the test used to determine this parameter. It was introduced in 1909.[2]


  • Mechanism of The DLCO Test 1
  • Factors affecting DLCO 2
    • Decrease 2.1
    • Increase 2.2
  • Factors affected by DLCO 3
    • Decrease 3.1
  • References 4
  • External links 5

Mechanism of The DLCO Test

This test involves measuring the partial pressure difference between inspired and expired carbon monoxide. It relies on the strong affinity and large absorption capacity of erythrocytes for carbon monoxide and thus demonstrates gas uptake by the capillaries that are less dependent on cardiac output.[3] The measurement of DLCO is affected by atmospheric pressure and/or altitude and correction factors can be calculated using the method recommended by the American Thoracic Society.[4] Expected DLCO is also affected by the amount of hemoglobin, carboxyhemoglobin, age and sex. The correction for hemoglobin is based on the method of Cotes[5][6] as recommended by the American Thoracic Society. Online resources exist to facilitate these corrections for altitude, hemoglobin, and carboxyhemoglobin.

Factors affecting DLCO


DLCO is decreased in any condition which affects the effective alveolar surface area:

  1. Hindrance in the alveolar wall. e.g. fibrosis, alveolitis, vasculitis
  2. Decrease of total lung area, e.g. Restrictive lung disease
  3. Chronic obstructive pulmonary disease (COPD), due to large residual air stuck in the lungs
  4. Uneven spread of air in lungs, e.g. emphysema
  5. Pulmonary embolism
  6. Cardiac insufficiency
  7. Pulmonary hypertension
  8. Bleomycin (upon administration of more than 200 units)
  9. Chronic heart failure[7]
  10. Anemia-due to decrease in blood volume
  11. Amiodarone high cumulative dose; more than 400 milligrams per day

However, many modern devices compensates for the hemoglobin value of the patient (taken by blood test), and excludes it as a factor in the DLCO interpretation.


Factors that can increase the DLCO include polycythaemia, asthma (can also have normal DLCO) and increased pulmonary blood volume as occurs in exercise. Other factors are left to right intracardiac shunting, and alveolar hemorrhage.[8]

Factors affected by DLCO


A DLCO of less than 60% predicted portends a poor prognosis for lung cancer resection. FEV1 is of lesser prognostic value for lung resection survival.[9]


  1. ^ Macintyre N, Crapo RO, Viegi G; et al. (October 2005). "Standardisation of the single-breath determination of carbon monoxide uptake in the lung". Eur. Respir. J. 26 (4): 720–35.  
  2. ^ Hughes J, Bates D (2003). "Historical review: the carbon monoxide diffusing capacity (DLCO) and its membrane (DM) and red cell (Theta.Vc) components". Respir Physiol Neurobiol 138 (2-3): 115–42.  
  3. ^ Sue DY, Oren A, Hansen JE & Wasserman K (1987). Diffusing capacity for carbon monoxide as a predictor of gas exchange during exercise. N. Engl. J. Med., 316(21):1301-1306.
  4. ^ American Thoracic society, Single Breath Carbon Monoxide Diffusing Capacity (transfer factor) Recommendations for a Standard Technique- 1995 Update, Am J Respir Crit Care Med. 152 pp 2185-2198 (1995).
  5. ^ J.E. Cotes 1993, Lung Function, 5th Edition., Blackwell Scientific Publications, London
  6. ^ J.E. Cotes, J.M. Dabbs, P.C. Elwood, A.M. Hall, A. McDonald, and M.J. Saunders. Iron-deficiency anaemia: its effects on transfer factor for the lung (diffusing capacity) and ventilation and cardiac frequency during submaximal exercise. Clin. Sci. 42:325-33 (1972).
  7. ^
  8. ^ Ruppel, G. L. (2009). Manual of Pulmonary Function Testing. ISBN 978-0-323-05212-2
  9. ^ Diffusion lung capacity for carbon monoxide (DLCO) is an independent prognostic factor for long-term survival after curative lung resection for cancer (p n/a) Michael J. Liptay, Sanjib Basu, Michael C. Hoaglin, Neil Freedman, L. Penfield Faber, William H. Warren, Zane T. Hammoud, Anthony W. Kim. Journal of Surgical Oncology. Published Online: Oct 1 2009 8:20AM doi:10.1002/jso.21407

External links

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.